CYCLIN-DEPENDENT KINASE INHIBITORS - A NE W FAMILY OF CELL-CYCLE REGULATORS

Cyclin-dependent protein kinases (CDK) are essential cell cycle regula tors that have been identified in every eukaryotic species. A new fami ly of CDKs regulators, called cyclin-dependant kinases inhibitors (CKI ), has been recently identified in yeast and mammals. Here we review o ur current knowledge on the characteristics and putative functions of these regulators. Most of them exhibit a kinase inhibitory function at the G1-to S-phase transition and therefore appear to play key roles i n the connection between growth and cell cycle control. Furthermore, t heir possible involvement in tumorogenesis are making them potential m embers of the tumour suppressor genes family.